The present invention relates to the technical sector relating to methods used for supplying liquefied petrol gas (LPG) to vehicles using petrol-fuelled engines.

In particular, the present invention concerns a system for supplying petrol-fuelled vehicles with liquefied petroleum gas (LPG), a system usable both for supplying low- pressure type petrol-fuelled engines, i.e. engines having indirect injection (single-point, multi-point, for example), or which are still provided with carburettors or kj-tronic mechanical injection pumps, and for fuelling vehicles with petrol engines of the high- pressure type, i.e. engines having direct injection into the combustion chamber.

The present invention further relates to an installation module for adapting petrol-· driven vehicles with liquefied petroleum gas (LPG).

^A In the following the initials LPG will be used to indicate liquefied petroleum gas as a type of liquid fuel.

DESCRIPTION OF THE PRIOR ART

Methods are already known for adapting petrol-driven vehicles in circulation to LPG as ÷ a liquid fuel, in place of petrol.

The use of methods enabling LPG to be used as a liquid fuel for fuelling vehicles with engines originally conceived for supply only by petrol, not only as a source of savings - _s in running costs, also has the aim of obtaining satisfactory performance of the engines, i.e. not much inferior to the performances usually given during petrol-fuelled driving.

The methods usually employed include recourse to the use of an LPG tank to be installed in the vehicle, an LPG tank which includes, internally thereof, sunk in the LPG, the LPG fuel supply pump and the need to use and install a further fuel supply channel, in addition to the petrol supply channel, or to mechanically modify the existing channel with additional mechanical parts, for the supply of LPG alone to the injection device-motor group present in the vehicle.

These methods exhibit however various drawbacks. A first drawback relates, naturally, to safety, as the LPG supply pump is situated directly sunk into the LPG internally of the LPG tank, a position with requires setting up adequate safety measures and protections which, over time, might become inadequate.

A second drawback relates to the functioning of the engine when supplied exclusively with LPG.

In fact, in this type of supply (only LPG as a liquid fuel) it has been found that the engine does not exhibit a constant, continuous and fluid functioning, as in the case of petrol supply, exhibiting a reduction in power, with a consequent loss of fluidity especially in the passage from low revolutions to high revolutions.

This non-constant and non-continuous functioning is determined by the circumstance that in consequence of the emptying of the LPG tank during LPG supply, the outlet pressure of the LPG from the tank is notably reduced: for example, it can go from a pressure of about 10 bar, with the tank more or less full, to a pressure of about 2-3 bar when the tank is almost empty.

Therefore, consequently, as the LPG supply pump present in the tank provides a constant head, i.e. giving the LPG a fixed and constant pressure increase, it is not able to compensate for the different LPG pressure values and will supply to the injection device-motor group LPG progressively exhibiting different and falling pressure.

This further leads to the impossibility of being able to directly control and regulate not only the pressure values but also the quantity of LPG that is sent to the injection- device-motor group, with the consequent need to intervene and modify the electronic management system of injection originally included and set for supplying petrol as well as necessarily having to proceed, as mentioned above, to installation of a special LPG supply channel to the injection device-motor device group in addition to the one included for supply of petrol.

Lastly, a particularly important problem encountered in the methods at present used occurs during the step of transition and return from LPG supply to petrol supply: during the passage and switching from LPG supply to petrol supply, the lowering of the pressure values which happens in the combustion chamber of the engine determines the formation of LPG in the gaseous state.

The presence of LPG in the gaseous state constitutes an obstacle to normal fuel supply in the injection device-motor group on the part of the fuel pump present in the petrol supply circuit, with a consequent malfunctioning of the engine.

In fact, the petrol supply pressure given by the petrol pump (usually in the order of 3.5- 4 bar) is not sufficient to evacuate the residues of gaseous LPG, which remain internally of the injection device-motor group, in particular inside the injection device, and prevent the correct supply of the petrol: in practice, the thrust given by the petrol pump is not alone sufficient for the petrol to be thrust into the injection device due to the presence of LPG in the gaseous state which prevents or obstructs the inlet.

SUMMARY OF THE INVENTION

The aim of the present invention is therefore to provide a new system for supplying petrol vehicles with liquefied petrol gas (LPG) able to obviate the above-cited drawbacks in the prior art methods.

In particular, an aim of the present invention is to provide a system which enables sending LPG at a constant pressure, to the injection device-motor group, i.e. guaranteeing an LPG supply with a constant pressure, independently of the degree of fullness of the LPG tank, and which enables, during the switching and returning step from LPG to petrol supply, freeing the injection device-motor group of the presence of LPG in the gaseous state, thus guaranteeing normal inflow and supply of the petrol.

The above aims are entirely attained according to the contents of claim 1.

The system disclosed with the present invention can be used both for adapting petrol- engine vehicles already in commerce to LPG use as a liquid fuel in place of the petrol and is usable and installable directly during the production step in order to enable production and sale of vehicles having motors already predisposed for double supply with petrol and LPG.

Other special characteristics of the system of the present invention are set out in the various claims dependent on claim 1.

A further aim of the present invention is to provide an installation module which enables adapting vehicles with petrol motors to liquefied petrol gas (LPG) supply rapidly and efficiently, reducing the hours of labour required for the adapting, and which enables using the petrol supply channel already present in the vehicle for LPG supply to the injection device - motor group of the vehicle.

This aim is obtained according to the contents of claim 9.

Other special characteristics of the installation module are set out in the various claims dependent on claim 9.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristics of the invention will emerge from the following description of preferred embodiments of the supply system and the installation module of the invention, made with reference to the accompanying figures of the drawings in which: figures from 1 to 4 illustrate a preferred embodiment of the system and module of the invention usable when petrol vehicles include a control of the petrol pressure/quantity value to be supplied to the motor at and before the petrol supply pump (PB) and comprise a petrol return channel (R) from the petrol supply pump (PB) to the petrol tank (S); in figures 1-4 the original and usual petrol supply circuit is illustrated with a more heavily marked line; in each of figures 1-4, the different configuration of the system components are illustrated, as well as the module in relation to the various operating steps in use of the vehicle (LPG supply: figure 1; LPG-petrol passage step figure 2; petrol supply: figure 3; petrol-LPG passage: figure 4);

figures 5-9 illustrate a -preferred embodiment of the system and the module of .ihe invention usable when petrol vehicles include a control of the petrol pressure/quantity value to be supplied to the motor internally of the injection device -motor group (M) and include a petrol return channel (RB) from the group (M) to the petrol tank (S); in figures 5-9 the original and usual petrol supply circuit is illustrated with a more heavily marked line, while in each of figures 5-9 the different configurations of the various system components and the module are illustrated, in relation to the different operating steps of use of the vehicle (LPG supply: figure 5; LPG-petrol passage step 1: figure 6; LPG-petrol passage step 2: figure 7; petrol supply: figure 8; petrol-LPG passage: figure 9).

DESCRIPTION OF PREFERRED EMBODIMENTS

In the accompanying figures of the drawings, reference numeral (100) denotes the system for supplying petrol vehicles with liquefied petrol gas (LPG) object of the present invention.

This system, as mentioned in the preamble hereto, is usable both for vehicles predisposed with a petrol motor of the low-pressure type, i.e. with a motor that includes indirect injection (single-point, multi-point for example), or which is still provided with a carburettor, with supply pressure values of about 1.5-7.5 bar, or which is usable with vehicles having petrol motors of the high-pressure type, i.e. with a motor including direct injection in the combustion chamber, and with supply pressure values of the order to 50 - 180, 200 bar, thanks to the presence of a high-pressure injection pump internally of the injection device for raising the pressure of the petrol received from the petrol supply pump.

Consequently, in the accompanying figures, the injection device-motor group (M) generally present in petrol vehicles is denoted, where the concept is intended to cover both the case of low-pressure and high-pressure petrol motors.

As mentioned herein above, the term LPG is meant to indicate fuel in the liquid state, i.e. liquefied petrol gas; therefore in the description that follows and in the claims, the term LPG should be taken to mean liquid LPG.

Thus, vehicles destined to be adapted to LPG supply by means of the system (100) of the present invention, are of a type comprising an injection device-motor group (M), a tank (S) for the petrol, a pump (PB) for supplying the petrol, communicating with the tank (S), and a petrol supply channel (CB), interposed between the petrol pump (PB) and the injection device-motor group (M), for supplying petrol to the group (M).

The system (100) proposed by the present invention comprises:

- an LPG recipient (G),

- an LPG supply pump (PG), external of the LPG recipient,

- a first fluid passage circuit (1) comprising a first solenoid valve (V1) and a sealed containing portion (11) for containing LPG at a constant pressure, the first fluid passage circuit (1) being interposable between, and connectable to, the LPG recipient (G) and the LPG supply pump (PG) such that the sealed containing portion (11) communicates with the LPG supply pump (PG) and the first solenoid valve (V1) is interposed between the recipient (G) and the portion (11);

- a first pressure detecting sensor (P1), the first sensor (P1) being provided for detecting a pressure value of the LPG present internally of the sealed containing portion (11) such that the first solenoid valve (V1) can be commandable such as to regulate the outlet of LPG from the LPG recipient (G) and to regulate the injection of the LPG internally of the sealed containing portion (11) in such a way as to guarantee a continuous presence of LPG at a constant pressure in the sealed containing portion (11) and thus a continuous LPG supply at constant-pressure to the LPG supply pump (PG);

- a second fluid passage circuit (2), the second fluid passage circuit (2) being interposable between, and connectable to, the LPG supply pump (PG) and the petrol supply channel (CB) to the injection device-motor group (M), the second fluid passage circuit (2) comprising a second solenoid valve (V2) commandable such as to enable the LPG supply pump (PG) to supply the injection device-motor group (M) with constant-pressure LPG collected from the sealed containing portion (11) when the vehicle is to be supplied only with LPG.

In this way, the system (100) of the present invention advantageously enables continuously and controlledly predisposing of LPG at constant pressure internally of the sealed containing portion (11) of the first circuit (1): this enables the LPG supply pump (PG) to source LPG at a constant pressure from the portion (11) and supply it, via the second circuit (2), to the petrol supply channel (CB) for supplying the injection- device motor group (M) of the vehicle.

In this way the supply of the group (M) with LPG is guaranteed at a constant pressure value, as in the case of supply only with petrol.

In this regard, the first solenoid valve (V1) is continuously commanded to open/close, including in proportion or intermittently, i.e. partially open/partially closed (that is, commanded such as to set in connection or interrupt the connection between the LPG recipient (G) with the sealed containing portion (11) depending on the pressure detected by the first sensor (P1), such that in the containing portion (11) there is a continuous presence of LPG at a constant pressure (in this regard, in figure 1 and figure 4 the opening position of the first solenoid valve (V1) has been illustrated in a dotted line).

Firstly, this circumstance enables using the petrol supply channel (CB) for LPG supply, without therefore having to carry out invasive interventions on the injection device (such as perforating the injectors) nor predisposing a special further supply channel only for the ' LPG, and, second, a homogeneous functioning of the motor is guaranteed, as if it were supplied with petrol.

This is because the LPG at constant pressure which is aspirated by the containing portion (11) by means of the LPG supply pump (PG) undergoes a pressure increase given by the pump (PG) (an increase for example of 12 bar): this pressure increase given by the liquid LPG enables bringing the specific weight of the LPG almost to the specific weig ht of the petrol .

Further, it is possible to use the settings already present in the electronic control board predisposed in the vehicle concerning the management/control of the injection times in all the injection plants. The proposed system (100) of the present invention exhibits the specific speciality of further comprising:

- a third fluid passage circuit (3) communicating with the sealed containing portion (11) and connectable with the petrol supply channel (CB), in a position at the outlet of the petrol supply pump (PB), the third fluid passage circuit (3) comprising a third solenoid valve (V3), the third solenoid valve (V3) being commandable to enable, during the step of switching and passage from LPG supply to petrol supply (see figure 2 and figure 6), placing the petrol supply pump (PB) in series with the LPG supply pump (PG) and enabling inflow of petrol from the petrol supply pump (PB) into the containing portion (11) in such a way that the petrol can be supplied to the injection device-motor group (M) through the second fluid passage circuit (2), by means of both the pump (PB) and the pump (PG) with a pressure which is such as to push any LPG in the gaseous state present internally of the group (M) to exit from the group (M), and a fourth fluid passage circuit (4) in order to enable return of the LPG in the gaseous state, pushed out from the injection device-motor group (M), to the LPG recipient (G).

The specific peculiarity of including the third circuit (3) and the fourth circuit (4), and placing in series the petrol supply pump (PB) with the LPG supply pump (PG) enables, when the passage from LPG supply to petrol supply takes place, using the two pumps (the pump (PB) and the pump (PG) contemporaneously in series for sending the petrol to the injection-motor device group (M); in this way the petrol can be supplied to the group (M) with a pressure value that is greater than the case of supply with only the petrol supply pump present in the vehicle.

This means that the petrol supplied at a greater pressure, when it reaches the injection device-motor group (M), can push any gaseous LPG that might have been formed during the switching step out of the group (M), due to the inevitable pressure drop internally of the group (M).

Instead, in the prior art, in switching from LPG supply to petrol supply, the petrol is fed in only using the petrol pump, which operates at pressure values of about 3.5-4 bar and therefore does not impress on the petrol, which is sent to the injection device- motor group, a thrust/force/pressure necessary such as to cause any gaseous LPG to exit.

With the present invention, the circumstance of setting two pumps in communication and in series, i.e. the petrol supply pump (PB) with the LPG supply pump (PG), advantageously enables, in switching from LPG to petrol supply, being able to send petrol to the injection device-motor group (M), with a much higher pressure value, increased by about 12 bar thanks to the LPG supply pump (PG).

This special detail is also enabled by the fact of being able to use the second circuit (2), normally used for LPG supply, which is directly connected to the petrol supply channel (CB), as mentioned above, thanks to the possibility of having available an LPG source at a constant pressure contained in the sealed containing portion (11) of the first circuit (1).

Other further details characteristic of the system (100) of the present invention are as follows.

The system (100) is provided with a second pressure detecting sensor (P2) provided such as to detect the pressure of the petrol supplied to the injection device-motor group (M) from the petrol supply pump (PB) and the LPG supply pump (PG), when placed in series with one another by means of the third circuit (3) through the second fluid passage circuit (2) and in that the fourth fluid passage circuit (4) comprises a fourth solenoid valve (V4) commandable such as to enable or interrupt connection of the fourth circuit (4) with the LPG recipient (G).

In particular, when during LPG functioning it is desired to pass to petrol supply, the third solenoid valve (V3) of the third circuit (3) is commanded to connect the petrol supply channel (V3) to the containing portion (11), i.e. place the petrol supply pump (PB) in series with the LPG supply pump (PG) while the fourth solenoid valve (V4) is commanded to set the fourth circuit (4) in communication with the recipient (G) of LPG so that the LPG in the gaseous state, pushed out of the injection device-motor group ( ), can be returned to the LPG recipient (G).

In this step, any quantities of petrol that might, together with the gaseous LPG, reach the recipient (G) of LPG, will deposit on the bottom, due to the greater specific weight, and will be newly sent to the engine at the following activation of the sole LPG supply.

When the second pressure sensor (P2) detects that the pressure value of the petrol thus supplied to the injection device-motor group (M) exhibits a value that is equal to the original pressure in conditions of petrol supply, the fourth solenoid valve (V4) is commanded to interrupt the connection of the fourth circuit (4) with the LPG recipient (G).

The system (100) also has a fifth fluid passage circuit (5) interposable and connectable between the LPG supply pump (PG) and the LPG recipient (G), the fifth fluid passage circuit (5) comprising a fifth solenoid valve (V5). The fifth solenoid valve (V5) is commandable, during supply of petrol to the vehicle, such as to place the LPG supply pump (PG) in connection with the LPG recipient (G) in such a way as to enable early activation of the LPG supply pump (PG), of the first solenoid valve (V1 ) and the first LPG pressure detecting sensor (P1) such as to guarantee a ready presence of LPG at a constant pressure in the sealed containing portion (11) when passage is required from petrol supply to LPG supply (see figure 4 and figure 9).

The system (100) also has a sixth solenoid valve (V6) installable along the petrol supply channel (CB) in a position downstream of the connecting point of the third fluid passage circuit (3) with the petrol supply channel (CB).

The presence of the, sixth solenoid valve (V6) is for interrupting the connection between the petrol supply pump (PB) and the injection device-motor group (M) when the petrol supply pump (PB) is placed in series to the LPG supply pump (PG) via the third fluid passage circuit (3) (see figures 2 and 6) or when the vehicle is supplied with LPG (see figure 1 , figure 6).

In the case of petrol vehicles including a control of the pressure/quantity pressure value of petrol to be supplied to the engine at the petrol supply pump PB and comprise a petrol return channel (R) from the petrol supply pump (PB) to the petrol tank (S) (see figures from 1 to 4), the system (100) of the present invention includes positioning and connecting the fourth fluid passage circuit (4) between the petrol supply channel (CB) and the LPG recipient (G).

The fourth circuit (4), during the LPG supply functioning, can also enable regulating the LPG injection pressure (see for example the description in reference to figure 1 in the following).

When the petrol vehicles comprise a control of the petrol supply pressure value internally to be supplied to the engine internally of the injection device-motor group (M) and comprise a petrol return channel (RB) from the group (M) to the petrol tank (S) (see figures from 5 to 9), the system (100) includes positioning and connecting the fourth fluid passage circuit (4) between the petrol return channel (RB) and the LPG recipient (G).

In this case, the system (100) also comprises a seventh solenoid valve (V7) installable along the petrol return channel (RB), the seventh solenoid valve (V7) being commandable such as to interrupt the connection between the injection device-motor group (M) and the petrol tank (S), when the fourth solenoid valve (V4) is commanded to connect the petrol return channel (RB) to the LPG recipient (G). This situation can occur for example during the passage step from LPG supply to petrol supply, when it is necessary to source the LPG in gaseous state from the injection device-motor group (M) and send it to the LPG recipient (G) (see for example figure 6) or during LPG supply only, when any eventual excess of LPG has to be able to return to the LPG recipient (G) (see for example figure 5).

The seventh solenoid valve (V7) is then commandable such as to reset the connection between the petrol return channel (RB) and the petrol tank (S) during the petrol supply.

Further, still in reference to the above case (i.e. vehicle with control of the pressure/quantity of petrol to be supplied to the engine internal of the injection device- motor group (M)), the system (100) is also provided with a sixth fluid passage circuit (6) which is connectable between the petrol supply channel (CB) and the petrol return channel (RB).

The sixth fluid passage circuit (6) comprises an eighth solenoid valve (V8) commandable such as to place the petrol supply pump (PB) in communication with the petrol return channel (RB) when the vehicle is supplied with only LPG (see figure 5); this enables keeping the petrol supply pump (PB) active and functioning even during only LPG supply, a circumstance which brings the advantage of maintaining unchanged the petrol supply pump (PB) management parameters set in the control board.

Naturally, even though not mentioned above, all the system components (100) are connectable and interfaceable electrically with the management control board present in the vehicle and are further interfaceable, again electrically, with a special button or other type of command such as to activate the passages from one type of supply to the other (see for example the broken lines in the various figures symbolising the possible electrical connections).

The above-mentioned sensor (P1) is a sensor of the type able to detect not only the pressure but also the temperature of the LPG present internal of the sealed containing portion (11); this provides the possibility of monitoring, controlling and also regulating the state of the LPG internally of the portion (11).

The invention also relates, as evidenced above, to providing an installation module for converting petrol supplied vehicles to supply with liquefied petrol gas (LPG).

The installation module of the invention is constituted by a container (10), which container (10) has been summarily and schematically represented in the appended figures, by way of example, by a closed pathway in dashed-and-dotted lines.

The essential characteristics of the installation module are constituted by the fact that the module comprises, internally of the container (10);

- a first fluid passage circuit (1) comprising a first solenoid valve (V1) and a sealed containing portion (11) for containing LPG at a constant pressure, the first fluid passage circuit (1) being accessible from outside the container (10) for connecting with an LPG recipient and usable for receiving LPG and for continuously storing LPG at a constant pressure internally of the sealed containing portion (11);

- a first pressure detecting sensor (P1), usable for detecting the LPG pressure value present internally of the sealed containing portion (11) and for command of the first solenoid valve (V1) such as to regulate inflow of LPG into the containing portion (11) such that LPG is present at a constant pressure in the containing portion (11);

- a second fluid passage circuit (2), comprising a second solenoid valve (V2), the second circuit (2) being accessible from outside the container (10) for connection with the petrol supply channel (CB) to the injection device-motor group (M) present in the vehicle and usable for receiving LPG at a constant pressure and for conveying the LPG to the supply channel (CB);

- a third fluid passage circuit (3), comprising a third solenoid valve (V3) and communicating with the sealed containing portion (11) of the first fluid passage circuit (1), the third circuit (3) being accessible from outside the container (10) and usable for placing the petrol supply channel (CB) of the vehicle in communication, downstream of the petrol supply pump (PB) of the vehicle, with the containing portion (11);

- a fourth fluid passage circuit (4), comprising a fourth solenoid valve (V4), the fourth circuit (4) being accessible from outside the container (10) for connection with the LPG recipient and usable to enable return of any LPG in the gaseous state, pushed out from the injection device-motor group (M), to the LPG recipient.

In a preferred embodiment, such as the one for example illustrated in the appended figures, the installation module comprises, internally of the container (10), a pump (PG) interposable and connectable between the containing portion (11) of the first circuit (1 ) and the second solenoid valve (2) of the second circuit (2).

For example, the pump (PG) is advantageously constituted by a double-screw counter-rotating pump.

In this preferred embodiment, where the module already internally comprises a pump (PG), other characteristics of the installation module are as follows: the first fluid passage circuit (1) comprises a first connecting element (a), accessible from outside, for enabling connection of the first solenoid valve (V1) of the first fluid passage circuit (11) with the LPG recipient, and a second connecting element (b) for enabling connection of the sealed connecting portion (11) of LPG at constant pressure with the pump (PG);

- the second fluid passage circuit (2) comprises a third connecting element (c) for enabling connection of the second fluid passage circuit (2) with the pump (PG), and a fourth connecting element (d), accessible from outside, for enabling connection of the second circuit (2) with the petrol supply channel (CB) to the injection device-motor group (M) present in the vehicle;

- the third fluid passage circuit (3) comprises a fifth connecting element (e) accessible from outside the container (10), for enabling connection of the third fluid passage circuit (3) to the petrol supply channel (CB) present in the vehicle;

- the fourth fluid passage circuit (4) comprises a sixth connecting element (f) and a seventh connecting element (g), accessible from outside, for enabling connection of the fourth fiuid passage circuit (4) between the injection device-motor group (M) present in the vehicle and the LPG recipient (G).

In a further possible embodiment (not illustrated in the accompanying figures), the installation module is usable for connecting to an external fluid supply pump (PG); in this case the second connecting element (b) of the first circuit (1 ) will be predisposed such as to be accessible from outside of the container (10), in order to enable the connection between the portion (11) and the pump (PG), such that the third connecting element (c) of the second circuit (2) will be predisposed such as to be accessible from outside the container (10), such as to enable connection of the second circuit (2) with the pump (PG).

The installation module further comprises, in both possible embodiments mentioned above (with the pump (PG) comprised internally of the container, or with the pump (PG) external of the container), a second pressure detecting sensor (P2) internal of the container, provided for detecting the pressure of the petrol supplied to the injection device-motor group (M) through the second fluid passage circuit (2) when the third solenoid valve (V3) of the third fluid passage circuit (3) is commanded such as to place the petrol supply channel (CB) of the vehicle in communication with the containing portion (11) and to place the petrol supply pump (PB) in series with the pump (PG).

The installation module further comprises, internally of the container (10), in both possible above-mentioned embodiments: a fifth fluid passage circuit (5), comprising a fifth solenoid valve (V5), usable, during petrol functioning of the vehicle, for receiving LPG from the pump (PG) such as to enable early activation of the pump (PG), of the first solenoid valve (V1) and the first pressure detecting sensor (P1) such as to guarantee ready presence of LPG at a constant pressure in the sealed containing portion (11) of the first fluid passage circuit (1 ), when passage from petrol supply to LPG supply is requested.

In this regard, the fifth circuit (5) comprises an eighth connecting element (h) for enabling connection of the fifth circuit (5) with the pump (PG), and a ninth connecting element (i), accessible from outside, for enabling connection of the fifth circuit (5) with the LPG recipient (G) such as to enable return of the LPG into the recipient (G).

The module further comprises, in both possible above-indicated embodiments, internally of the container (10), a sixth solenoid valve (V6) and a tenth connecting element (m) and an eleventh connecting element (n), accessible from outside such as to enable connection of the sixth solenoid valve (V6) to the petrol supply channel (CB) in a position downstream of the connecting point of the third fluid passage circuit (3) with the petrol supply channel (CB).

The predisposing of the sixth solenoid valve (V6) enables interrupting connection between the petrol supply pump (PB) and the injection device-motor group (M) when the petrol pump (PB) is placed in series with the LPG supply pump (PG) via the third fluid passage circuit (3), or when the vehicle is to be supplied only with LPG.

Though not described in detail, the module will include all the electrical connections for connecting the various components present internally of the container (10) with the management and control board present in the vehicle with the special button or other type of command provided for passage from one supply type to the other (see for example the broken lines in the various figures symbolising the possible electric connections).

In the following the functioning of the system (100) object of the invention will be described, first with reference to figures 1-4 (the case in which petrol-fuelled vehicles include a control of the petrol pressure/quantity value to be supplied to the motor at the petrol supply pump (PB)) and then with reference to figures 5-9 (the case in which petrol vehicles include a control of the petrol pressure/quantity value of the petrol to be supplied to the motor internally of the injection device-motor group ( )).

Figure 1 , LPG supply of the injection device-motor group (M) Figure 1 illustrates the configurations assumed by the various system components (100) when the supply to the vehicle is set to LPG supply.

In this situation the second solenoid valve (V2) of the second circuit (2) is commanded to be "opened" i.e. such as to place the LPG supply pump (PG) in communication with the supply channel (CB) which leads to the injection device -motor group (M) while the sensor (P1) detects the pressure value internally of the sealed containing portion (11) of the first circuit (1) so that the first solenoid valve (V1) of the first circuit (1) can be commandable for regulating the inflow of LPG from the LPG recipient (G) such that there is always LPG at a constant pressure in the portion (11) (for example the management and control board can be regulated such that the functioning of the sensor (P1) and the first solenoid valve (V1) are set so as to maintain the LPG pressure internally of the containing portion (11 ) at a value of from 3-4 bar to 7 bar).

The third solenoid valve (V3) of the third circuit is "closed" as is the fifth solenoid valve (V5) of the fifth circuit (5) and also the sixth solenoid valve (V6), along the petrol supply channel (CB), is "closed" such as to interrupt the connection between the petrol pump (PB) and the group (M).

In this case, the petrol pump (PB) can continue to function, as there is a petrol return to the petrol tank (S) by means of the petrol return channel (R) already present originally in the vehicle.

Should the quantity of LPG thus supplied to the injection device - motor group (M) be in excess and consequently the pressure reach too-high values, the second pressure detecting sensor (P2) can detect this situation and consequently the fourth solenoid valve (V4) of the fourth circuit (4) can be temporarily activated (i.e. "opened") such as to place the group (M) in communication with LPG recipient (G) for return of the excessive LPG to the recipient.

The pump (PG) elevates the pressure of the LPG aspirated from the sealed containing portion (11) with a positive increase of pressure (DELTAP) of from +2 a +10 bar, and therefore the LPG injection pressure to the motor injection device is given by the sum of the pressure value present internally of the portion (11) and the increase supplied by the pump (PG).

Figure 2, switching from LPG supply to petrol supply

When the command is activated for the switch from LPG supply to petrol supply, the first solenoid valve (V1) of the first circuit (1) is "closed" i.e. commanded to interrupt inflow of LPG from the LPG recipient (G) to the sealed containing portion (11) while the third solenoid valve (V3) of the third circuit is "opened", i.e. commanded such as to place the petrol supply channel (CB) in communication with the containing portion (11) and place the petrol supply pump (PB) in series with the LPG supply pump (PG).

As mentioned above, as the petrol supply pump (PB) is functioning during the LPG supply, the petrol is immediately pushed, and flows into the containing portion (11) in order to be aspirated by the pump (PG) and thus sent via the second circuit (2) to the injection device-motor group (M).

In this way the petrol is sent to the group (M) through the pump (PB) and the pump (PG), thus with a pressure that is higher than with the pump (PB) alone: in this way the inflow of petrol at a higher pressure in the group (M) enables pushing out of the group any gaseous LPG which might have formed in the group during the preceding function or at the start of the switch.

For this purpose, the fourth solenoid (V4) of the fourth circuit is "opened", i.e. is commanded to place the group (M) in communication with the recipient (G) of LPG in order to enable the LPG in the gaseous state to be conveyed to the recipient (G).

The possible quantity of petrol that might inflow to the LPG recipient (G) constitutes no problem as, due to the greater specific weight, it will be deposited in the bottom of the recipient (G) and will be aspirated when the vehicle returns to LPG functioning.

Figure 3, petrol supply

The third solenoid valve (V3) is "closed", i.e. is commanded to interrupt the connection between the petrol supply channel (CB) and the containing portion, the second solenoid valve (V2) of the second circuit is "closed", i.e. it is commanded to interrupt the connection between the LPG supply pump (PG) and the petrol supply channel (CB), the fourth solenoid valve (V4) of the fourth circuit is also "closed", while the sixth solenoid valve (V6) along the channel (CB) is "opened" i.e. commanded to restore the connection between the petrol supply pump (PB) and the group (M).

In this situation the LPG supply pump (PG) can be turned off and made inactive up to the following activation when LPG supply is to be restored.

Figure 4. switching from petrol supply to LPG supply

When the command for activating the switch from petrol supply to LPG supply is activated, a preliminary step is comprised, illustrated in figure 4, during which the continuous presence of LPG is recreated at a constant pressure internally of the sealed containing portion (11) before the actual sending of LPG to the group (M).

For this purpose, the fifth solenoid valve (V5) of the fifth circuit (5) is "opened", i.e. is commanded to set the LPG supply pump (PG) in communication with the LPG recipient (G), the pump (PG) is newly reactivated while the first solenoid valve (V1), on the basis of the data detected by the first sensor (P1), is commanded to regulate the inflow of LPG from the LPG recipient (G) in the containing portion (11) such that the continuous presence of LPG at a constant pressure is guaranteed.

In this step, the vehicle continues to be supplied with petrol as in figure 3.

When the sixth solenoid valve (V6) is "closed", i.e. commanded such as to interrupt the connection between the petrol pump (PB) and the group (M), and the second solenoid valve (V2) of the second circuit is "opened", i.e. commanded such as to place the LPG supply pump (PG) in communication with the group (M), this special detail enables having the LPG immediately available at the optimal pressure to guarantee continuity and homogeneity of the motor during the change of the type of liquid fuel (from petrol to LPG).

At the same time the fifth solenoid valve (V5) of the fifth circuit (5) is "closed" i.e. commanded to interrupt the connection between the LPG supply pump (PG) with the LPG recipient (G); thus the configuration of the various components of the system illustrated in figure 1 is restored.

Figure 5, LPG supply to the injection device-motor group (M)

The first solenoid valve (V1 ) of the first circuit (1) is commanded, on the basis of data detected by the first sensor (P1 ), to regulate the inflow of LPG from the LPG recipient (G) to the sealed containing portion (11) such that there is LPG at constant pressure therein; the second solenoid valve (V2) is "opened", i.e. it places the LPG supply pump (PG) in communication with the supply channel (CB) of the injection device- motor group ( ).

The sixth solenoid valve (V6) is "closed", i.e. commanded to interrupt the connection between the petrol supply pump (PB) and the group (M), while the eighth solenoid valve (V8) of the sixth circuit (6) is "opened", i.e. commanded to enable the pump (PB) to continue to function and enable return of the pumped petrol from the pump (PB) to the tank.

The fourth solenoid valve (V4) of the fourth circuit is "opened" while the seventh solenoid valve is "closed" such that the group (M) is placed in communication with the LPG recipient (G) such that any eventual excess of LPG sent to the group (M), or when the second sensor (P2) or the pressure control system already present internally of the group (M) detects pressure values that are too high, can be sent towards the LPG recipient (G).

Figure 6, switching from LPG supply to petrol supply, first step

When the command for the passage from LPG supply to petrol supply is activated, the first solenoid valve (V1) of the first circuit (1) is "closed", i.e. it is commanded to interrupt the inflow of LPG from the recipient (G) to the sealed containing portion (11), the eighth solenoid valve (V8) of the sixth circuit (6) is "closed" such as to interrupt the petrol return connection from the pump (PB) to the petrol tank (S), while the third solenoid valve (V3) of the third circuit (3) is "opened", i.e. commanded to place the pump (PB) in communication with the sealed containing portion (11), i.e. to set the pump (PB) in series with the pump (PG).

The petrol is then pushed from the two pumps through the second circuit (2) to the group (M).

The fourth solenoid valve (V4) is "opened" while the seventh solenoid valve (V7) is "closed" such that any gaseous LPG present internally of the group (M), pushed out of the group (M) by the arrival of the petrol, can be newly directed to the LPG recipient (G).

As above described in relation to the description of figure 2, any quantities of petrol that might be directed to the LPG recipient (G) do not constitute any problem.

The considerations made during the description of the functioning of figure 2 are true in this case too.

Figure 7, switching from LPG supply to petrol supply, second step

Thereafter, the fourth solenoid valve (V4) of the fourth circuit is "closed", i.e. commanded to interrupt connection between the petrol return channel (RB) and the LPG recipient (G), i.e. the connection between the group (M) and the recipient (G), while the seventh solenoid valve (V7) is "opened", i.e. commanded to set the petrol return circuit (RB) in communication with the petrol tank (S) such that should the control system of the pressure/quantity value of the petrol present in the group (M) detect an excessive petrol quantity/pressure, the petrol can be directed via the return channel (RB) newly to the petrol tank (S).

Figure 8, petrol supply

When the second sensor (P2) detects a pressure value equal or close to the pressure value originally established for the usual petrol supply to the motor, the sixth solenoid valve (V6) is "opened", i.e. commanded to set the petrol supply pump (PB) in communication with the group (M), via the petrol supply channel (CB), while the third solenoid valve (V3) of the third circuit (3) is "closed", i.e. commanded such as to interrupt the connection between the petrol supply pump (PB) and the sealed containing portion (11), such that the group (M) is supplied by the pump (PB) via the channel (CB), i.e. via the ordinary petrol circuit.

The second solenoid valve (V2) of the second circuit (2) is simultaneously "closed", i.e. commanded to interrupt the connection between the pump (PG) and the petrol supply channel (CB), while the pump (PG) can be deactivated.

In this configuration the vehicle is supplied with petrol using the original petrol circuit.

Figure 9, switching from petrol supply to LPG supply

In this figure, the same operations as those described with reference to figure 4 are repeated, finalised at making LPG at constant pressure available in the sealed containing portion (11) before the effective interruption of the connection of the petrol supply pump (PB) with the group (M) and the activation of the connection between the LPG supply pump (PG) and the group (M).

The effective passage of the LPG supply (i.e. the return to the configuration of figure 5) is done by "closing" the sixth solenoid valve (V6), i.e. commanding it such as to interrupt the connection between the petrol supply pump (PB) and the group (M) and "opening" the second valve (V2) of the second circuit, i.e. commanding it such as to set the LPG supply pump (PG) in connection with the group (M).

It is specified that even though not described herein above, the system comprises the presence of anti-flow-inversion valves, i.e. single-acting, predisposed downstream of each of the above-cited solenoid valve, as illustrated in the accompanying figures.

The LPG supply pump (PG) used in the system of the present invention is advantageously constituted by a double-screw counter-rotating pump.

The system of the present invention thus enables using the original petrol supply channel (identified with reference CB) for supply of the LPG too; thanks to the sealed containing portion (11) a continuous source of LPG at constant pressure can be predisposed, which enables having available a control on the LPG supply pressure independently of the LPG tank pressure.

This further leads to the considerable advantage of being able to continue using the settings already present in the management and control board of the vehicle, as there is no change in the injection times originally set for petrol supply, as well as avoiding having to perform invasive installation operations which require several working hours (for example such as perforating the injection devices). It is once more emphasised that the system provided by the present invention has the peculiarity of setting the petrol supply pump (PB) is series with the LPG supply pump (PG), in the step of switching and passage from LPG supply to petrol supply, so that the petrol can be supplied to the injection device-motor group (M) by the combined action of the two pumps, with a greater pressure than that which would occur if only the petrol supply pump (PB) were used: this advantageously enables pushing out gaseous-state LPG from the group, and guarantees an optimal and homogeneous functioning of the motor without jerks or power reduction or loss of revolutions.

In fact, this operation would not be possible if the petrol were supplied to the group (M) only from the pump (PB), as happens in the prior art methods.

The small and not invasive installation module disclosed in the present invention enables adapting petrol-fuelled vehicles to be supplied with LPG rapidly and simply, with the need for only minimal interventions.

The above has been described by way of non-limiting example, and any constructional variants are understood to fall within the scope of the following claims.